Thorns
Gives attackers a Level × 15% chance of suffering 1–5 HP of reflected damage when they hit the wearer, regardless of whether the attack was melee or ranged. Each armor piece with Thorns rolls independently, so stacking it across slots increases proc chance.
Best uses
Most effective on a chestplate (the primary enchanting-table item for Thorns) combined with high Unbreaking, since each proc also damages the armor's durability. Useful for mob farms and PvP, though the durability cost means Unbreaking III is nearly mandatory alongside it.
How to get Thorns
Enchanting table (chestplate is the primary item; other armor slots are secondary and typically require an anvil and an enchanted book), librarian villager trades, and structure loot. Level III may need to be applied via anvil on many armor tiers.